CDK12 and breast cancer: CDK12 can phosphorylate RNA polymerase II to regulate transcription elongation, and it can also play a key role in RNA splicing, DNA-damage response (DDR) and the maintenance of genome stability.318,319 It is overexpressed in breast cancer, ovarian cancer, prostate cancer and other cancers, and is a valuable target for cancer valuable.318 Loss of CDK12 function by silencing and using selective covalent CDK12/13 inhibitor THZ531 leads to a decrease in DDR-associated genes transcription and increases sensitivity to PARP inhibitors and platinum chemotherapy.